Test: Class 7 General Science NCERT Based - 2


25 Questions MCQ Test Science & Technology for UPSC CSE | Test: Class 7 General Science NCERT Based - 2


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This mock test of Test: Class 7 General Science NCERT Based - 2 for UPSC helps you for every UPSC entrance exam. This contains 25 Multiple Choice Questions for UPSC Test: Class 7 General Science NCERT Based - 2 (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Class 7 General Science NCERT Based - 2 quiz give you a good mix of easy questions and tough questions. UPSC students definitely take this Test: Class 7 General Science NCERT Based - 2 exercise for a better result in the exam. You can find other Test: Class 7 General Science NCERT Based - 2 extra questions, long questions & short questions for UPSC on EduRev as well by searching above.
QUESTION: 1

Consider the following assertions :

1. The heat flows from a hotter object to a colder object.

2. The mode of heat transfer that continues till the whole water gets heated is known as convection.

3. The process by which heat is transferred from the hotter end to the colder end of an object is known as the conduction.

Which of the above assertions is/are correct?

Solution:
  • Heat Transfer: The movement of heat from a warmer object to a colder one – when two substances at different temperatures are mixed together, heat flows from the warmer body to the cooler body until they reach the same temperature (Zeroth Law of

  • Thermodynamics – Thermal Equilibrium). Part of the heat lost by the warmer body is transferred to the cooler body and part is lost to the surrounding object or the air.

  • Convection is the process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. The initial heat transfer between the object and the fluid takes place through conduction, but the bulk heat transfer happens due to the motion of the fluid.

    • Convection is the process of heat transfer in fluids by the actual motion of matter.

    • It happens in liquids and gases.

    • It may be natural or forced.

    • It involves a bulk transfer of portions of the fluid.

  • Conduction is the transfer of energy in the form of heat or electricity from one atom to another within an object by direct contact. Conduction occurs in solids, liquids, and gases. However, solids transfer energy most efficiently since the molecules in solids are most tightly packed, and the molecules are closer together, as shown in this figure. For liquids and gases, the density of the particles are generally lower than those of solids and the particles are farther apart, so the energy transfer is less efficient.

QUESTION: 2

Match List I to List II and select the correct answer with the code given below:

Solution:
  • During the day, the land gets heated faster than the water. The air over the land becomes hotter and rises up. The cooler air from the sea rushes in towards the land to take its place. The warm air from the land moves towards the sea to complete the cycle. The air from the sea is called the sea breeze.

  • To receive the cooler sea breeze, the windows of the houses in coastal areas are made to face the sea. At night it is exactly the reverse. The water cools down more slowly than the land.

  • So, the cool air from the land moves towards the sea. This is called the land breeze. Dark surfaces absorb more heat and, therefore, we feel comfortable with dark coloured clothes in the winter. Light coloured clothes reflect most of the heat that falls on them and, therefore, we feel more comfortable wearing them in the summer.

QUESTION: 3

An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will

Solution: Heat flows from a body of higher temperature to a body of lower temperature. Here the temperature of both the objects is the same. So, heat will not flow from one object to another or there will not be any change in the temperature of both the two objects.

QUESTION: 4

More is the difference in temperature of the bodies in contact:

Solution: More is the rate of flow of heat from a body at a higher temperature to a body at lower temperature.

QUESTION: 5

Which of the following pairs may give equal numerical values of the temperature of a body?

Solution:
QUESTION: 6

Match List I to List II and select the correct answer with the code given below:

Solution:

These substances taste sour because they contain acids, whereas the substances which are bitter in taste and feel soapy on touch are known as bases. The names of some major acids and related substances are: Name of acid Found in

1. Acetic acid Vinegar

2. Formic acid Ant’s sting

3. Citric acid Citrus fruits such as oranges, lemons, etc.

4. Lactic acid Curd

5. Oxalic acid Spinach

6. Ascorbic acid Amla, Citrus fruits (Vitamin C)

7. Tartaric acid Tamarind, grapes, unripe mangoes, etc. All the acids mentioned above occur in nature.

Name of base Found in

1. Calcium hydroxide : Lime water

2. Ammonium hydroxide : Window cleaner

3. Sodium hydroxide/Potassium hydroxide: Soap

4. Magnesium hydroxide: Milk of magnesia

 

 

QUESTION: 7

Consider the following assertions:

1. The solutions which do not change the colour of either red or blue litmus are known as neutral solutions.

2. Turmeric, litmus, china rose petals are some of the naturally occurring indicators.

3. When acid content is high in rainwater, then it is called acid rain.

Which of the above assertions is/are correct?

Solution:
  • Neutral solution is a solution whose pH is close to 7. They prefer remaining at a perfect balance.Usually a neutral solution is neither acidic nor basic. It doesn't imply that the neutral solution lacks charged ions.

  • Natural Indicator is a type of indicator that can be found naturally and can determine whether the substance is an acidic substance or a basic substance. Some examples of natural indicators are red cabbage, turmeric, grape juice, turnip skin, curry powder, cherries, beetroots, onion, tomato, etc.

  • Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog, hail or even dust that is acidic.

  • Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents. The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids. These then mix with water and other materials before falling to the ground.

  • While a small portion of the SO2 and NOX that cause acid rain is from natural sources such as volcanoes, most of it comes from the burning of fossil fuels.

QUESTION: 8

Which of the following assertions is/are correct with reference to soil treatment due to excessive use of chemical fertilisers?

1. Excessive use of chemical fertilisers makes the soil acidic.

2. If the soil is acidic, organic matter is added to it.

Use the code given below to select the correct answer :

Solution: Excessive use of chemical fertilisers makes the soil acidic. Plants do not grow well when the soil is either too acidic or too basic. When the soil is too acidic, it is treated with bases like quicklime (calcium oxide) or slaked lime (calcium hydroxide). If the soil is basic, organic matter (compost) is added to it. Organic matter releases acids which neutralises the basic nature of the soil.

QUESTION: 9

Regarding the examples of neutralisation in Everyday Life, consider the following assertions :

1. The waste of many factories contain acids; therefore, they are neutralised by adding basic substances before they are allowed to flow into the water bodies.

2. Magnesium hydroxide neutralises the effect of excessive acid in the stomach.

3. The effect of the acid injected into the skin through an ant bite can be neutralised by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution.

Which of the above assertions is /are correct?

Solution:
  • The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic substances.

  • Our stomach contains hydrochloric acid. It helps us to digest food. But too much acid in the stomach causes indigestion, which is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralises the effect of excessive acid.

  • When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.

QUESTION: 10

Which of the following examples is/are related to physical change?

1. Tearing of paper

2. Change in color

3. Combining of Hydrogen and Oxygen to form water

4. Burning of paper

Use the code given below to select the correct answer :

Solution: In tearing of paper, it had undergone changes in size. Properties such as shape,size,colour,state of a substance are called physical properties. A change in which a substance undergoes a change in its physical properties is called a physical change. Rest, other changes are the examples of chemical change.

QUESTION: 11

In terms of physical and chemical changes, which of the following assertions is/are correct?

1. All physical changes are irreversible, while chemical changes are reversible.

2. The following may accompany a chemical change:-Sound may be produced, Heat, light or any other radiation (ultraviolet, for example) may be given or absorbed.

Use the code given below to select the correct answer :

Solution:
  • Physical changes: Changes in the Physical Properties of a Substance are known as Physical Changes. Physical Properties of a Substance include colour, size, shape, state, temperature, odour, appearance, texture and many more.

  • In addition, Physical Changes do not lead to the formation of new substances. Physical Changes may or may not be reversible. Examples of Physical Change

    • Breaking/Crushing of any Object

    • Expansion of Metal on Heating

    • Dissolving Sugar or Salt (Solute) in Water (Solvent) (as a result, a solution is formed)

    • Solidification of Molten Metal on Cooling

    • Shredding Paper

  • Chemical Changes: One or more substances, at times, react with one another or substances which are readily available in the environment. This consequently leads to the formation of a new substance(s). The formation of the new substance can also be accompanied by one or more of the following:

    1. Emission of Heat (Exothermic Reaction) as a result of a Chemical Changes

    2. Absorption of Heat (Endothermic Reaction) as a result of a Chemical Changes

    3. Emission Light as a result of a Chemical Changes

    4. Production of Sound as a result of a Chemical Changes

    5. Change or emission of Odour as a result of a Chemical Changes

    6. Emission of Gas as a result of a Chemical Changes

QUESTION: 12

Which of the following is not a physical change?

Solution: A physical change involves only change in physical state whereas a chemical change results in the formation of new substances. Boiling of water, melting of ice and dissolution of salt are physical changes as no new products are formed.

QUESTION: 13

Which of the following are exothermic processes?

1. Reaction of water with quicklime

2. Dilution of an acid

3. Evaporation of water

4. Sublimation of camphor (crystals)

Solution:
  • Exothermic reactions are reactions or processes that release energy, usually in the form of heat or light. In an exothermic reaction, energy is released because the total energy of the products is less than the total energy of the reactants.

  • For this reason, the change in enthalpy, [latex]\Delta H[/latex], for an exothermic reaction will always be negative. In the presence of water, a strong acid will dissociate quickly and release heat, so it is an exothermic reaction.

  • Endothermic reactions are reactions that require external energy, usually in the form of heat, for the reaction to proceed. Since endothermic reactions draw in heat from their surroundings, they tend to cause their environments to cool down.

  • They are also generally non-spontaneous, since endothermic reactions yield products that are higher in energy than the reactants. As such, the change in enthalpy for an endothermic reaction is always positive. In order to melt the ice cube, heat is required, so the process is endothermic.

QUESTION: 14

The process used to prevent rusting of iron, in which a thin coat of zinc is provided over the iron surface. This process is:

Solution:
  • Galvanizing, protection of iron or steel against exposure to the atmosphere and consequent rusting by application of a zinc coating. Properly applied, galvanizing may protect from atmospheric corrosion for 15 to 30 years or more.

  • As discontinuities or porosity develop in the coating, galvanic or electrolytic action ensues; the iron or steel, however, is protected by sacrificial corrosion, a phenomenon in which, as long as the zinc and the iron are in contact, atmospheric oxidation spares the iron and affects the zinc.

QUESTION: 15

Which statement is correct regarding acids?

1. Acid is a molecule which donate protons or accept electron pairs in reactions.

2. Acid increases the concentration of hydrogen atoms or hydronium atoms in water.

3. Acids have pH value less than 7.

4. Acid in the stomach helps in the digestion of food.

Use correct statements:

Solution:
  • Acid, any substance that in water solution tastes sour, changes the colour of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen, reacts with bases to form salts, and promotes certain chemical reactions (acid catalysis).

  • Examples of acids include the inorganic substances known as the mineral acids—sulfuric, nitric, hydrochloric, and phosphoric acids—and the organic compounds belonging to the carboxylic acid, sulfonic acid, and phenol groups.

  • Acids may be identified as either strong or weak acids based on how completely they dissociate into their ions in water.

  • A strong acid, such as hydrochloric acid, completely dissociates into its ions in water.

  • A weak acid only partly dissociates into its ions, so the solution contains water, ions, and the acid (e.g., acetic acid).

QUESTION: 16

Regarding the weather and climate, consider the following assertions —

1. The day-to-day condition of the atmosphere at a place with respect to the temperature, humidity, rainfall, wind speed, etc., is called the weather at that place.

2. The average weather pattern taken over a long time, say 30 years, is called the climate of the place.

Which of the above assertions is/are correct?

Solution:
  • Weather is the day-to-day state of the atmosphere, and its short-term variation in minutes to weeks. People generally think of weather as the combination of temperature, humidity, precipitation, cloudiness, visibility, and wind. Climate is the weather of a place averaged over a period of time, often 30 years.

  • Climate information includes the statistical weather information that tells us about the normal weather, as well as the range of weather extremes for a location.

QUESTION: 17

In the context of polar areas, consider the following assertions :

1. There happens to be six months of day and six months of night.

2. These regions are covered with snow and the temperature can be as low as –37 °C during winters.

3. Polar bears, penguins and reindeer are found here.

4. Many birds migrate to warmer regions when winter sets in.

Which of the above statements is correct?

Solution:
  • The polar regions present an extreme climate. These regions are covered with snow and it is very cold for most part of the year.

  • For six months the sun does not set at the poles while for the other six months the sun does not rise.

  • In winters, the temperature can be as low as –37°C. Animals living there have adapted to these severe conditions.Birds migrate to warmer regions when winter sets in. They come back after the winter is over.

QUESTION: 18

Which of the following assertions is/are true, in terms of tropical region?

1. The climate of these areas is generally hot.

2. These regions get plenty of rainfall.

3. Tropical rain forests are found in Western Ghats and Assam in India.

4. Lion tailed macaque (also called Beard ape) lives in the rainforests of Western Ghats.

Use the code given below to select the correct answer :

Solution:
  • The tropical region has generally a hot climate because of its location around the equator. Even in the coldest month the temperature is generally higher than about 15°C. During hot summers, the temperature may cross 40°C.

  • Days and nights are almost equal in length throughout the year. These regions get plenty of rainfall.

  • An important feature of this region is the tropical rainforests. Tropical rainforests are found in Western Ghats and Assam in India, Southeast Asia, Central America and Central Africa.

  • The lion-tailed macaque (also called Beard ape) lives in the rainforests of Western Ghats. Its most outstanding feature is the silver-white mane, which surrounds the head from the cheeks down to its chin. It is a good climber feeds mainly on fruits, seeds, young leaves, stems, flowers and buds. This beard ape also searches for insects under the bark of the trees. Since it is able to get sufficient food on the trees, it rarely comes down on the ground.

QUESTION: 19

Consider the following assertion and reason carefully:

Assertion: The moving air is called the wind.

Reason: Air moves from the region where the air pressure is high to the region where the pressure is low.

Use the code given below to select the correct answer :

Solution:
  • Wind is the movement of air caused by the uneven heating of the Earth by the sun. It does not have much substance—you cannot see it or hold it—but you can feel its force.

  • Warm equatorial air rises higher into the atmosphere and migrates toward the poles. This is a low-pressure system.

  • At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air. This is a high-pressure system. Winds generally blow from high-pressure areas to low-pressure areas. The boundary between these two areas is called a front.

  • The complex relationships between fronts cause different types of wind and weather patterns. Prevailing winds are winds that blow from a single direction over a specific area of the Earth.

QUESTION: 20

Consider the following assertions :

1. The regions close to the equator get maximum heat from the Sun.

2. The warm air rises, and the cooler air from the regions in the 0-30 degrees latitude belt, moves in the equator from the 30 degree side.

3. Due to the uneven heating of 30° to 60° latitude, the wind flows from 60° latitude to 30° latitude.

Which of the above assertions is/are correct?

Solution:
  • The Sun's rays are straight at the equator, so the areas around the equator receive maximum heat. The warm air rises, and the cooler air from the regions in the 0–30 degrees latitude belt on either side of the equator moves in.

  • These winds blow from the north and the south towards the equator. At the poles, the air is colder than that at latitudes about 60 degrees.

  • The warm air at these latitudes rises up and the cold wind from the polar regions rushes in, to take its place. In this way, wind circulation is set up from the poles to the warmer latitudes.

QUESTION: 21

In the context of wind flow, which of the following assertions is/are true?

1. In winter, the wind flows from the land to the ocean.

2. In summers, the wind flows from the oceans towards the land.

3. The winds from the oceans carry water vapour and bring rain. It is a part of the water cycle.

Use the code given below to select the correct answer :

Solution:
  • In summer, near the equator the land warms up faster and most of the time the temperature of the land is higher than that of water in the oceans. The air over the land gets heated and rises.

  • This causes the winds to flow from the oceans towards the land. These are monsoon winds. In winter, the direction of the wind flow gets reversed; it flows from the land to the ocean.The winds from the oceans carry water and bring rain. It is a part of the water cycle. The monsoon winds carry water and it rains.

QUESTION: 22

Consider the following assertions in the context of thunderstorms and cyclones —

1. The swift movement of the falling water droplets along with the rising air create lightning and sound, is called a thunderstorm.

2. The centre of a cyclone is a calm area.

Which of the above assertions is/are correct?

Solution:
  • These winds carry water droplets upwards, where they freeze, and fall down again. The swift movement of the falling water droplets along with the rising air create lightning and sound. It is this event that we call a thunderstorm.

  • The centre of a cyclone is a calm area. It is called the eye of the storm. A large cyclone is a violently rotating mass of air in the atmosphere, 10 to 15 km high. The diameter of the eye varies from 10 to 30 km.

  • It is a region free of clouds and has light winds. Around this calm and clear eye, there is a cloud region of about 150 km in size. In this region there are high-speed winds (150–250 km/h) and thick clouds with heavy rain. Away from this region the wind speed gradually decreases. The formation of a cyclone is a very complex process.

QUESTION: 23

In the context of cyclones, which of the following assertions is/are correct?

1. The western coast of India is more sensitive than the eastern coast in both strength and frequency of cyclones.

2. It is called a ‘hurricane’ in the American continent. In the Philippines and Japan it is called a 'typhoon'.

Use the code given below to select the correct answer :

Solution:
  • India's coast is extremely vulnerable to cyclones. With a coastline of 7517 km, the country is exposed to nearly 10 percent of the world's tropical cyclones.

  • Although cyclones affect the entire coast of India, the eastern coast is significantly more prone to cyclones as compared to the western coast.

  • The East coast of India faces the Bay of Bengal while the west coast of India is situated on the shores of Arabian Sea.

  • It is called a ‘hurricane’ in the American continent. In the Philippines and Japan it is called a 'typhoon'

QUESTION: 24

Consider the following statement about tropical cyclone

1. It is characterised by a low-pressure centre.

2. In this, counter clockwise wind flow in the Northern Hemisphere and clockwise wind flow in the Southern Hemisphere.

3. It is a warm core storm system.

Which of the above statements are correct?

Solution:
  • A tropical cyclone is a storm system, characterised by a low-pressure centre surrounded by a spiral arrangement of thunderstorms that produce strong winds and heavy rain.

  • A characteristic feature of tropical cyclones is the eye, a central region of clear skies, warm temperatures, and low atmospheric pressure.

  • Typically, atmospheric pressure at the surface of Earth is about 1,000 millibars. At the centre of a tropical cyclone, however, it is typically around 960 millibars, and in a very intense “super typhoon” of the western Pacific it may be as low as 880 millibars.

  • In addition to low pressure at the centre, there is also a rapid variation of pressure across the storm, with most of the variation occurring near the centre.

QUESTION: 25

Consider the following factors causes an increase in salinity of ocean water:

1. High temperature

2. High humidity

3. Pressure of winds

4. Presence of river mouths

Which of the statement(s) given above is/are correct?

Solution: In general, the higher the temperature the higher is the evaporation, but if humidity is high, evaporation is not higher even if the temperature is high. Thus, equatorial regions with higher temperature, but higher humidity do not have high salinity.